KINESIOL 2Y03 Lecture Notes - Lecture 20: Neurotransmission, Active Transport, Resting Potential

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indigohornet100

22 Oct 2017

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The charge difference across a plasma membrane. The transmission of an ap - neuron to neuron, neuron to tissue. Electricity is determined by two things: (1) the membrane potential and (2) membrane permeability. Na+/k+ is fuelled by active transport (requires atp) 1 atp - 3 na out, 2 k in. Through controlling which ion channels are open/ closed. Leaky channels: these are always open, they work with the pump to control resting membrane potential c. There are more k+ than na+ channels i. Ligand gated channel - responds to chemicals, neurotransmitters i: mechanical gated channel - responds to pressure, vibration, voltage gated channel - responds to change in membrane potential. The resting potential (-70 mv) is possible because of: The proteins inside the cell that are negative. The gated channels have a role in this after the membrane potential deviates from -70 mv to -50 mv.

Related Questions

1) Look up the structures of the following molecules. For each carbon atom, indicate its oxidation state. Calculate the average oxidation state of the carbon atoms in each.

Glucose

Pyruvic acid

Citric acid

Oxaloacetic acid

Carbon dioxide

2) Consider the following hypothetical cell. Initially, the cell has an equal number of positive and negative charges (cations and anions) on either side of its plasma membrane (extracellular, intracellular). There are equal concentrations of Na+, K+, and Cl- on either side of the plasma membrane. Consider the effects of the following events, in sequence, upon the ion concentrations and charge distributions (membrane electrical potential).

A. NKA proteins are activated in the plasma membrane. How does this affect the ions and the membrane electrical properties?

B. A small number of K+ channels open in the plasma membrane. How does this affect the ions and the membrane electrical properties?

C. An even larger number of Na+ channels open in the plasma membrane.

D. The Na+ and K+ channels close. Cl- channels open.

3) Pancreatic juice contains approximately 150 mM Na+. How do these Na+ ions contribute to the absorption of amino acids and sugars? Explain how 100% of an amino acid can be absorbed from the small intestines. HINT: intestinal epithelial cells have NKA, numerous cotransporters (symporters) and facilitated diffusion proteins.

1. The plasma membrane of liver cells contains a glucose uniportthat transports glucose by facilitated diffusion. When the[glucose] is higher inside the liver cell than the [glucose]outside the liver cell, the glucose uniport will

A. couple the transport of glucose out of the cell to thehydrolysis of ATP

B. couple the transport of glucose into the cell to thehydrolysis of ATP

C. switch to a closed conformation, allowing no transport ofglucose

D. transport glucose out of the cell by passive transport

E. transport glucose in of the cell by passive transport

2. Unlike the positive charged ion shown in the middle diagramof figure 11-4B, K+ is higher in concentration inside the cell. Howwill the membrane potential of a cell at rest (shown in both themiddle and right-hand diagrams of Figure 11-4B) affect theelectrochemical gradient for K+?

A. The membrane potential will increase the electrochemicalgradient

B. The membrane potential will decrease the electrochemicalgradient

C. The membrane potential will have no effect on theelectrochemical gradient

3. Which of the following proteins carries out activetransport?

A. gluclose symport

B. Bacteriorhodopsin

C. ABC transporter

D. NA K pump

E. All of the above

4. Aquaporin will not transport Na+ ions because

A. Two asparagine residues in the channel prevent the passage ofNa+ ions by binding the oxygen of each water molecule as it passesby

B. Na+ ions are repelled by the positive charges at the entranceto the channel

C. Na+ ions cannot make contact with the carbonyl (C=O) groupson all four sides of the channel

D. The passage of Na+ ions is energetically unfavorable becauseone side of the channel is hydrophobic in nature

5. The acetylcholine receptor is different from other channelproteins we have discussed, such as the K+ leak channel,because

A. The acetylcholine channel is composed of a single polypeptiderather than multiple subunits

B. The acetylcholine channel transports Na+ ions against theconcentration gradient for sodium

C. The acetylcholine channel has a much smaller diameter thanother channel proteins

D. The acetylcholine channel transports ions with theirassociated shell of water molecules

E. The acetylcholine channel is always open, and never switchesto a closed conformation

6. After opening briefly along the axon of a neuron,voltage-gated ion channels switch to an inactivated conformationthat slowly returns to the original closed conformation of theprotein. This slow change in conformation, requiring about amillisecond, is important because

A. all of the ions that were transported across the membranewhen the ion channels were open must be actively transported backto the other side of the membrane, restoring the originalconcentration gradient, before the ion channels can open again

B. ATP hydrolysis is necessary to drive this energeticallyunfavorable change in conformation

C. it prevents the action potential from reversing direction andtraveling back toward the cell body of the neuron

D. the channel protein must be dephosphorylated in order tocomplete the transport process and return to the originalnonphosphorylated conformation

limeelephant476

QUESTION 1

Ion diffusion across plasma membrane needs

		a concentration gradient across the membrane
		specific transporters
		ATP
		provide extra energy for the transport

2 points

QUESTION 2

There are four types of large biological molecules

2 points

QUESTION 3

Active transporters transport substances across cell membrane against ____________

2 points

QUESTION 4

Which of the following is a nonpolar amino acid?

	1.	Valine
	2.	Serine
	3.	Aspartic acid
	4.	Glutamic acid

2 points

QUESTION 5

Membrane potential of a cell is created by:

	1.	sodium ion concentration difference between inside and outside of the cell
	2.	a difference in protein concentration across the cell membrane
	3.	an electrical potential difference between the intracellular fluid and the surrounding extracellular fluid
	4.	a difference between the potassium concentration inside and outside of the cell

2 points

QUESTION 6

A mutation resulted in a change from a valine to a glutamic acid in a peptide sequence. This mutation will NOT change the protein folding

True

False

2 points

QUESTION 7

Ions can be transported across plasma membrane by

	1.	diffusion
	2.	No need of transporters
	3.	osmosis
	4.	active transport

2 points

QUESTION 8

Phospholipid is composed of

	1.	A glycerol backbone
	2.	One protein group
	3.	One carbohydrate group
	4.	Two fatty acid chains and one phosphate group

2 points

QUESTION 9

Prokaryotic cells and eukaryotic cells are similar in

	1.	Plasma membrane
	2.	nucleus
	3.	mechanism for protein translation
	4.	endoplasmic reticulum

2 points

QUESTION 10

Disulfide bonds are formed between two histidine residues

True

False

KINESIOL 2Y03 Lecture Notes - Lecture 20: Neurotransmission, Active Transport, Resting Potential

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